[gta02-core] GSM modem [was Re. Status & next milestone for GTA02-core?]

Werner Almesberger werner at openmoko.org
Mon Aug 3 16:29:20 CEST 2009

?lvaro Lopes wrote:
> I'll be honest here. Even at "typical" consumption the Option chip seems
> to draw up to 1.1A @ 3.6V.

I think this is maximum average (over some period of time) current.
E.g., when sending, you wouldn't draw more than 4 Ws within a 1 s
interval, some of which will be in the form of 3A spikes.

> True, but USB is less error-prone, less sensitive to EMI.

Bah, if we can't get UART right over a few cm ... ;-) One problem
with USB is that it has periodic activity, even if "idle". So you
need elaborate fallback schemes to make it really stop doing

> As long as we can get the schematic "non-intrusive", meaning it does
> not require changing the already drawn ones.

Telit should be a fairly direct replacement for the Calypso.
Option would be worse, because it means that BT and modem need
to be rotated, since we only have a single USB bus. Also, I've
never seen our BT module being used with UART.

- Werner

More information about the gta02-core mailing list